The present invention provides a method and display for planning the direction and inclination of the trajectory of a well bore and in particular to a method and display for planning the direction and inclination of a well bore trajectory using graphical techniques.
Traditional well bore drilling practices attempted to drill wells as near to the vertical as possible. However, over the past 20 years, it has become common to drill directional or slanted wells in order to gain access to hydrocarbon deposits located underneath ground sites, where it was not feasible to set up a drilling rig. Directional drilling is the process of directing the well bore being drilled along a defined trajectory to a predetermined target. Because of these directional drilling capabilities, strong economic and environmental pressures have increased the desire for and use of directional drilling. As a result of these pressures, directional drilling is being applied in situations where it has not been common in the past. These new applications have caused well bore trajectories to become increasingly more complex.
The location of the trajectory of a well bore is determined by computing catesian coordinates from a set of curvilinear coordinates defined by a set of survey stations at various depths in the earth. Each survey station comprises of a measured depth from surface, an inclination, and an azimuth at a location along a well path. To convert information taken at survey stations into a well path in terms of curvilinear coordinates some method is implemented which makes a set of assumptions about the well path. The set of assumptions are related to the well path between the survey stations. Several methods related to processing a well plan have been used to date including average angle, tangential, balanced tangential, Mercury, radius of curvature, and minimum curvature. Only the radius of curvature method and the minimum curvature method produce a path that is acceptable for highly directional wells.
In recent years, well plans have become much more complex due to the reduction in technological limitations which have made such well plans difficult if not impossible to drill using previous or conventional technologies. The complexity of these designer wells has forced well planners to use planning tools that are in turn becoming more and more complex.
Today, well planning is typically done by tying together a series of curve and hold sections using a spreadsheet on which each row represents an individual section of the well. The trajectory planning workflow is usually done by adding sections, plotting the sections, editing numbers on the spreadsheet, and again plotting the sections. This procedure is done repeatedly until well planners obtain a satisfactory trajectory. With the ever increasing three dimensional (3D) nature of wells and the necessity to avoid existing wells, there remains a need for a new well planning method that can create, manipulate and edit well plans. One such method can be a new graphical method that can create and edit well plan trajectories in order to achieve an optimal plan more quickly and more effectively than is done today.
Many software products exist today to plan wells using a spreadsheet like interface. These programs include Rodan, Drilling Office, WellPlan, and SysDrill. Rodan is a graphical well planning program that allows the user to modify individual sections of a well, but it basically modifies the sections on the spreadsheet graphically. Even though these products have the capability to plan wells, there still remains a need for a well planning method that can enable a user to modify multiple sections of a well plan at once in an intuitive manner. The present method can address this need The method described herein is different in that the user can modify many sections of the well plan at once instead of modifying the well section by section. This method allows the user to very quickly create and modify a well for their specific needs.
It is an objective of the present invention to provide a method and display for graphically planning the trajectory of a well bore.
It is a second objective of the present invention to provide a method and display for graphically planning a well trajectory using control points that do not lie on the well plan.
It is a third objective of the present invention to provide a method and display for graphically modifying the trajectory of a well plan by manipulating the location of one or more coordinates that are related to one section of a well.
It is a fourth objective of the present invention to provide a method and display that can graphically determine the trajectory of a well plan based on the modification of one section of the well plan.
It is a fifth objective of the present invention to provide a method and display that can manipulate the position of all sections of a well plan by modifying points that lie on and off of the well plan.
It is a sixth objective of the present invention to provide a graphical well planning method and display that can manipulate multiple sections simultaneously to reflect the impact to the modification of one section of the well plan on the entire well plan.
The present invention provides a graphical method and display to design and modify the trajectory of a well bore. A well bore trajectory plan comprises hold (straight) and curve sections. Hold sections are generally described by specifying the attitude and length of the hold section. Curve sections can be described and represented in a variety of ways. One way is by specifying the starting attitude, the ending attitude and the curve length. The actual path of the curve section is generally dependent on the computation method used to describe the section. Two common methods of computing curves are the minimum curvature method and the radius of curvature method. In the minimum curvature method, curve sections have a constant radius of curvature. The preferred method of the present invention assumes curves are computed using minimum curvature.
The method of the present invention positions points at locations off of the well plan for each curve section where lines which are tangent to each respective curve section and which extend from the points at the start and end of each curve section intersect. These points are referred to as control points. For each curve, the distance along the lines from the control point to tangent points of the curve sections is always equal if the curvature is constant. By manipulating the control point and keeping the curvature of the curve section constant, at least three sections of a well plan (two hold section and the connecting curve section) can be manipulated at the same tine. When curve sections precede or follow the first or last hold section, respectively, up to five sections (curve, hold, curve, hold, curve) can be manipulated simultaneously. By just moving a control point in 2D or 3D space, the attitude of the both hold sections can change, and the lengths all of the sections of a well plan can be altered. Many aspects of the well plan can be quickly changed using the control points as described in the present invention.
In operation, the control points can be manipulated in certain pre-determined directions. Since the different sections of the well plan are connected, movement of one section can alter the sections adjacent to the modified section. Modification of multiple sections can enable well planners to quickly model the path of an entire well bore instead of a section-by-section approach.
In addition to modifying the well plan with movement of a control point, there are three additional items that can be graphically modified to manipulate the well plan. These items are the starting point and ending point of the plan and the curvature of the curve sections.